Physics Program with 12 GeV JLab

J. P. Chen, Jefferson LabEIC Workshop, APS-DNP/JPS Joint Meeting, 10/13/2009

Introduction and Overview

Nucleon Structure - Spin-Flavor Structure in Valance Region

Nucleon Structure - Generalized Parton Distributions

Nucleon Structure - Transverse Momentum Dependent Distributions

Nucleon Structure - Form Factors

Parity Violation Electron Scattering - Low Energy Test of Standard Model

Nuclear Physics: Hadronization, Short-Range Correlations, Few-Body

Exotic Meson Search: Gluon Excitations

•Acknowledgement: Some slides “borrowed” from colleague’s talks

QCD and Nucleon Structure• A major challenge in fundamental physics: Understand QCD in all regions, including strong (confinement) region

• Nucleon = u u d + sea + gluons• Structure mostly determined by strong interaction• Mass, charge, magnetic moment, spin, axial charge, tensor charge • Decomposition of each of the above fundamental quantities

Mass: ~1 GeV, but u/d quark mass only a few MeV each! Momentum: total quarks only carry ~ 50% Spin: ½, total quarks contribution only ~30% Spin Sum Rule

Tensor charge Transverse sum rule?• Multi-dimensional structure and distributions• Confinement -- QCD vacuum: gluon field and sea

Jefferson Lab Experimental Halls

HallA: two HRS’ Hall B:CLAS Hall C: HMS+SOS

6 GeV polarized CW electron beam Pol=85%, I=180A

Luminosity ~ 1039

Polarized ~ 1036

Will be upgraded to 12 GeV by ~ 2014

Hall A polarized 3He target

longitudinal, transverse and verticalLuminosity = 1036

P(in-beam) = 65%Effective polarized neutron

P=65%

@ I=15 uA

Hall B/C Polarized p/d target

• Polarized NH3/ND3 targets

• Luminosity ~ 1035 (Hall C), ~ 1034 (Hall B)• In-beam average polarization

70-90% for p, 30-40% for d

CHL-2CHL-2

Upgrade magnets Upgrade magnets and power suppliesand power supplies

Enhance equipment in Enhance equipment in existing hallsexisting halls

6 GeV CEBAF1112Add new hallAdd new hall

Experimental Halls

• (new) Hall D: linear polarized photon beam, Selonoid detetcor ­ GluoX collaboration: exotic meson spectroscopy gluon-quark hybrid, confinement

• Hall B: CLAS12­ GPDs, TMDs, …

• Hall C: Super HMS + existing HMS­ Form factors, structure functions, …

• Hall A: Dedicated devices + existing spectrometers­ Super BigBite, Solenoid, Moller Spectrometer­ SIDIS, PVDIS, …

Overview of Physics Program

• Gluonic Excitations and the Origin of Confinement • Nucleon Structure

• Quark spin-flavor structure in valence region• Deep Exclusive Reactions (DVCS, DVMP) to study GPDs • SIDIS to measure Transversity and TMDs• Form Factors – Constraints on the GPDs

• Symmetry Tests

• Parity violation to test Standard Model and precision study of hadronic physics • The Physics of Nuclei

• Medium Effects: Hadronization, EMC effects• Short-Range Correlations• Few-Body

12 GeV Upgrade Kinematical Reach

• Reach a broad DIS region • Decisive inclusive DIS

measurements at high-x • Precision Deep Exclusive

Reactions (e.x. DVCS) to study GPDs

• Precision SIDIS for transversity and TMDs

• Parity Violating DIS to test Standard Model and precision study of hadronic physics

Structure­Functions­at­High­x­

­­­­­­­­­Valence­Quark­Distributions­­­

Hall A 11 GeV with HRSBONUS at Hall B 11 GeV with CLAS12

F2n/F2

p d/u ratio at high-x

Hall­B­CLAS,­Phys.Lett.­B641­(2006)­11 Hall­A­E99-117,­PRL­92,­012004­(2004)­­­­­­­­­­­­­­­­­­­­­­­­­­­­PRC­70,­065207­(2004)­

JLab 6 GeV Results on A1 at high x

SU(6)

pQCD

Inclusive Hall A and B and Semi-Inclusive Hermes

BBS

BBS+OAM

F. Yuan, H. Avakian, S. Brodsky, and A. Deur, arXiv:0705.1553

Polarized Parton Distribution at Large xpQCD with Quark Orbital Angular Momentum

A1p at 11 GeV

Projections for JLab at 11 GeV

pQCD

SU(6)

u and d at JLab 11 GeV

Polarized Sea

JLab @11 GeV

Flavor Decomposition with SIDIS

Generalized­Parton­Distributions­

3-d­Quark-Gluon­Structure­of­the­Nucleon­­­

Beyond form factors and quark distributions – Generalized Parton Distributions (GPDs)

Proton form factors, transverse charge & current densities

X. Ji, D. Mueller, A. Radyushkin, …

M. Burkardt, … Interpretation in impact parameter space

Structure functions,quark longitudinalmomentum & helicity distributions

Correlated quark momentum and helicity distributions in transverse space - GPDs

GPDs & Deeply Virtual Exclusive Processes­

x

­Deeply Virtual Compton Scattering (DVCS)

t

x+ x-

H(x,,t), E(x,,t), . .

hard­vertices

– longitudinal momentum transfer

x – longitudinal quark momentum fraction

–t – Fourier conjugateto transverse impact parameter

“handbag” mechanism

xB

2-xB

=

Twist 2 contribution

Twist 3 contribution strongly suppressed

Hall A E00-110 Demonstrated HandbagDominance at Modest Q2

The Twist-2 term can be extracted accurately from the cross-section differenceDominance of twist-2 handbag dominance DVCS interpretation straightforward

Deeply Virtual Exclusive Processes - Kinematics Coverage of the 12 GeV Upgrade

JLab Upgrade

Upgraded­JLab­hascomplementary&­unique­capabilities

unique­to­JLaboverlap­with­other­experiments

High­xB­only­reachablewith­high­luminosity­H1,­ZEUS

DVCS/BH- Beam Asymmetry

With large acceptance,measure large Q2, xB, t ranges simultaneously.

A(Q2,xB,t) (Q2,xB,t)

(Q2,xB,t)

Ee = 11 GeV

ALU

CLAS12­– L/T Separation­­ep­­­­­­­ep

L

T

xB­=­0.3-0.4­-t­=­0.2-0.3GeV2

Other bins measured concurrently

Projections for 11 GeV(sample kinematics)

Single­Spin­Asymmetry­in­Semi-inclusive­DIS

Transverse­Momentum­Dependent­Distributions

“Leading-Twist” TMD Quark Distributions

Quark

Nucleon

Unpol.

Long.

Trans.

Unpol. Long. Trans.

JLab 6 GeV experiment (E06-010/06-011)

SSA in SIDIS n↑(e,e′π+/-) on a Transversely Polarized 3He Target

Collins

Sivers

First neutron (3He) measurement

Completed data taking in 2/2009

Spokespersons:X. Jiang (Los Alamos)J.P. Chen (JLab)E. Cisbani (INFN)H. Gao (Duke)J.-C. Peng (UIUC)

PhD Students:K. Allada (UKy)C. Dutta (UKy)J. Huang (MIT)J. Katich (W&M)X. Qian (Duke)Y. Wang (UIUC)Y. Zhang (Lanzhou)

3He target

12 GeV: Solenoid detector for SIDIS and PVDIS

GEMs

Gas Cerenkov

Calorimeter

GEMs

Projection vs PT and x for + (60 days)

• For one z bin

(0.5-0.6)

• Will obtain 4

z bins (0.3-0.7)

• Also - at same

time

• With upgraded

PID for K+ and K-

3-D Projections for Collins and Sivers Asymmetry (+)

Parity­Violating­Electron­Scattering­

Test­Standard­Model­and­Precision­Study­of­Hadron­Structure

Parity Violating DIS

C1u and C1d will be determined to high precision by Qweak, APV Cs

C2u and C2d are small and poorly known: one combination can be accessed in PV DIS

New physics such as compositeness, leptoquarks:

Deviations to C2u and C2d might be fractionally large

A

V

V

A

Moller PV is insensitive to the Cij

PVDIS with SoLID

• High Luminosity on LH2 & LD2

• Better than 1% errors for small bins

• x-range 0.25-0.75

• Moderate running times

Physics Implications

Examples:•1 TeV extra gauge bosons (model dependent)•TeV scale leptoquarks with specific chiral couplings

Unique, unmatched constraints on axial-vector quark couplings:Complementary to LHC direct searches

(2C2u-C2d)=0.012

(sin2W)=0.0009

PV DIS and Nucleon Structure

• PVDIS provide precision study of hadron structure:

– Higher twist effects– Charge Symmetry Violation (CSV)– d/u at high x

• JLab at 11 GeV offers new opportunities

– PV DIS can address issues directly• Luminosity and kinematic coverage• Outstanding opportunities for new discoveries• Provide confidence in electroweak measurement

Parity Violating Moller Scattering

QWe

modified

sin2W runs with Q2

• Semileptonic processes have theoretical uncertainties • E158 established running, probing vector boson loops• JLab measurement would have impact on discrepancy between leptonic and hadronic Z-pole measurements

(sin2W) ~ 0.0003Comparable to single collider measurements

Hadronization­in­Nuclear­SIDIS­

Quark­Propagation­Through­Nuclei

Nuclear­Deep­Inelastic­Scattering­and­Hadronization

We­can­learn­about­hadronization­distance­scales­and­reaction­mechanisms­from­semi-inclusive­nuclear­DIS

Nucleus­acts­as­a­spatial­filter­for­outgoing­hadronization­products

Initial­focus­on­properties­of­leading­hadron;­correlations­with­subleading­hadrons­and­softprotons­also­of­interest.

(GeV) z

Observables­–­Hadronic­Multiplicity­Ratio­(≈­medium-modified­fragmentation­function)

In general, h = , K, , p, .…

Significant dependence of R on Apz T ,,, 2

MustMust measure multi-variable dependence for stringent model tests!

<z>=0.3-0.42, <Q2>=2.2-3.5 <>=11.5-13.4, <Q2>=2.6-3.1

Each point is differential in Q2, , z, and A; all are acquired simultaneously

12

GeV

Anti

cipate

d D

ata

12

GeV

Anti

cipate

d D

ata

Summary• 12 GeV JLab with high luminosity (1039 unpol., 1036-1037 pol.) and

large acceptance will lead us to a new precision frontier • Provide precision data on multi-dimension nucleon structure and

a deep understanding of strong interaction:• Spin-flavor structure in the valence region • Generalized Parton Distributions with DVCS and limited DVMP • Transverse Spin and TMDs with SIDIS

• Parity violating electron scattering provide precision low-energy tests of standard model and a precision tool to study hadronic physics

• Precision Study of hadronization and nuclei medium effects• Other important physics opportunities:

• GlueX, Form Factors, Short-range Correlations, Few-Body, J/…

Strong Interaction and QCD

• A major challenge in fundamental physics: Understand QCD in all regions, including strong interaction (confinement) region

• Strong interaction, running coupling ~1 -- QCD: accepted theory for strong interaction -- asymptotic freedom (2004 Nobel) perturbation calculation works at high energy -- interaction significant at intermediate energy quark-gluon correlations -- interaction strong at low energy (nucleon size) confinement, chiral symmetry breaking

E

s

New Hall D, Enhanced Existing Halls A, B & C

9 GeV tagged polarized photons and a 4 hermetic detector

D

Super High Momentum Spectrometer (SHMS) at high luminosity and forward angles

C

CLAS upgraded to higher (1035 cm-2s-1) luminosity and coverage

B

Retain HRS Pair for continuation of research in which resolution comparable to nuclear level spacing is essential. Use Hall to stage “one-of-a-kind” specialized experiments requiring unique apparatus.

A

Why Are PDFs at High x Important?

• Valence quark dominance: simpler picture

-- direct comparison with nucleon structure models

SU(6) symmetry, broken SU(6), diquark• x 1 region amenable to pQCD analysis

-- hadron helicity conservation?• Clean connection with QCD, via lattice moments• Input for search for physics beyond the Standard Model at high

energy collider

-- evolution: high x at low Q2 low x at high Q2

-- small uncertainties amplified

-- example: HERA ‘anomaly’ (1998) • Input to nuclear, high energy physics calculations

Proton Neutron

World Data on A1

Color “Polarizabilities”Color “Polarizabilities”

E08-027 “g2p”SANE

“d2n” just completed in Hall A

6 GeV Experiments

Sane: just completed in Hall C

“g2p” in Hall A, 2011

projected

Jlab 6 GeV Results on d2

Color Polarizability d2n with JLab 12 GeV

• Projections with 12 GeV experiments Improved Lattice Calculation (QCDSF, hep-lat/0506017)

Link to DIS and Elastic Form Factors­

),,(~­,~­,­, txEHEH qqqq

JG = ­1

1

)0,,()0,,(21

21 xExHxdxJ qqq

Quark­angular­momentum­(Ji’s­sum­rule)

X.­Ji,­Phy.Rev.Lett.78,610(1997)­­

­­­­­­­­­­­­DIS­at­ =t=0

)(),()0,0,(~)(),()0,0,(

xqxqxH

xqxqxHq

q

Form­factors­(sum­rules)

)(),,(~­­­,­)(),,(~­

)­­Dirac­f.f.(),,(

,

1

1,

1

1

1

tGtxEdxtGtxHdx

tF1txHdx

qPq

qAq

q

q

)­­Pauli­f.f.(),,(1

tF2txEdxq

q

Access GPDs through DVCS x-section & asymmetries

Accessed­by­cross­sections

Accessed­by­beam/target­spin­asymmetry

t=0

Quark­distribution­q(x)

­-q(-x)

DIS measures at =0

DVCS interpreted in pQCD at Q2 > 1 GeV2

ALU E=5.75 GeV

<Q2> = 2.0GeV2

<x> = 0.3<-t> = 0.3GeV2

CLAS preliminary

[rad]

Pioneering DVCS experiments First GPD analyses­of­HERA/CLAS/HERMES data­in­LO/NLO consistent­with ~ 0.20.A.­Freund­(2003),­A.­Belitsky­et­al.­(2003)­­

Full GPD analysis needs high statistics and broad coverage

twist-3twist-2

AUL­=­sin­+­sin2

twist-3 contributions are small

CLAS12­- DVCS/BH Target Asymmetry

e­p­­­­­­­­ep

<Q2> = 2.0GeV2

<x> = 0.2<-t> = 0.25GeV2

CLAS preliminary

E=5.75 GeVAUL

Longitudinally polarized target

~sinIm{F1H+(F1+F2)H...}d~

E = 11 GeVL = 2x1035 cm-2s-1

T = 1000 hrsQ2 = 1GeV2

x = 0.05

DVCSDVCS DVMPDVMP

GPDs – Flavor separation

hard­vertices

hard­gluon

Photons cannot separate u/d quarkcontributions.

long.­only

M = select H, E, for u/d flavorsM = , K select H, E

transverse polarized target

3D Images of the Proton’s Quark Content

M. Burkardt PRD 66, 114005 (2002)

b - Impact parameterT

u(x,b )T d(x,b )T uX(x,b )T

dX(x,b )T

Hu EuNeeds: HdEd

quark flavor polarization

Accessed in Single Spin Asymmetries.

Transversity and TMDs

• Three twist-2 quark distributions (integrated over P┴) :

• Momentum distributions: q(x,Q2) = q↑(x) + q↓(x)• Longitudinal spin distributions: Δq(x,Q2) = q↑(x) - q↓(x)

• Transversity distributions: δq(x,Q2) = q┴(x) - q┬(x)

• Tensor charge: integral of transversity over x

• TMDs (without integrating over PT), 8 distributions + fragmentation functions:

• Distribution functions depends on x, k┴ and Q2 : δq, f1T┴ (x,k┴ ,Q2), …

• Fragmentation functions depends on z, p┴ and Q2 : D, H1(x,p┴ ,Q2)

• Measured asymmetries depends on x, z, P┴ and Q2 : Collins, Sivers, …

(k┴, p┴ and P┴ are related)

AUTsin() from transv. pol. H target

Simultaneous fit to sin( + s) and sin( - s)

`Collins‘ moments

• Non-zero Collins asymmetry

• Assume q(x) from model, then

H1_unfav ~ -H1_fav

• Need independent H1 (BELLE)

`Sivers‘ moments

•Sivers function nonzero (+) orbital angular momentum of quarks

•Regular flagmentation functions

PKU-RBRC Workshop on Transverse Spin Physics, June 30, 2008PKU-RBRC Workshop on Transverse Spin Physics, June 30, 2008 F. BradamanteF. Bradamante

Collins asymmetry – proton datacomparison with M. Anselmino et al. predictions Franco Bradamante

Transverse2008, Beijing

PKU-RBRC Workshop on Transverse Spin Physics, June 30, 2008PKU-RBRC Workshop on Transverse Spin Physics, June 30, 2008 F. BradamanteF. Bradamante

Sivers asymmetry – proton datacomparison with the most recent predictions from M. Anselmino et al. Franco Bradamante

Transverse2008, Beijing

Current Status• Large single spin asymmetry in pp->X• Collins Asymmetries

- sizable for proton (HERMES and COMPASS) large at high x, large for -

- and has opposite sign unfavored Collins fragmentation as large as favored (opposite sign)? - consistent with 0 for deuteron (COMPASS)

• Sivers Asymmetries - non-zero for + from proton (HERMES), consistent with zero (COMPASS)? - consistent with zero for - from proton and for all channels from deuteron - large for K+ ?

• Very active theoretical and experimental study RHIC-spin, JLab (Hall A 6 GeV, CLAS12, HallA/C 12 GeV), Belle, FAIR (PAX)

• Global Fits/models by Anselmino et al., Yuan et al. and …

• Solenoid with polarized 3He at JLab 12 GeV Unprecedented precision with high luminosity and large acceptance

Precision Study of Transversity and TMDs

• From exploration to precision study• Transversity: fundamental PDFs, tensor charge• TMDs provide 3-d structure information of the nucleon• Laboratory to study QCD• Learn about quark orbital angular momentum• Multi-dimensional mapping of TMDs

• 3-d (x,z,P┴ ) • Q2 dependence • multi facilities, global effort

• Precision high statistics• high luminosity and large acceptance

Discussion• Unprecedented precision 3-d mapping of SSA

• Collins, Sivers and other TMDs• +, - and K+, K-

• Study factorization with x and z-dependences • Study PT dependence• Combining with CLAS12 proton and world data

• extract transversity and fragmentation functions for both u and d quarks• determine tensor charge• study TMDs for both valence and sea quarks • study quark orbital angular momentum

• Combining with world data, especially data from high energy facilities• study Q2 evolution

• Global efforts (experimentalists and theorists), global analysis• much better understanding of 3-d nucleon structure and QCD

•The couplings depend on electroweak physics as well as on the weak vector and axial-vector hadronic current •Both new physics at high energy scales as well as interesting features of hadronic structure come into play•A program with many targets and a broad kinematic range can untangle the physics

(gAegV

T + gV

egAT)

PV Electron Scattering on Hadron

PAC34

Statistical Errors (%) vs Kinematics

4 months at 11 GeV

2 months at 6.6 GeV

Error bar σA/A (%)shown at center of binsin Q2, x

For SOLID Spectrometer

12 GeV PVDIS Sensitivity: C1 and C2 Plots

Cs

PVDIS

Qweak PVDIS

World’s data

Precision Data

6 GeV

CSV Theory and Data

MRST PDF global with fit of CSVMartin, Roberts, Stirling, Thorne [Eur Phys J C35, 325 (04)]:

Analytic calculation similar to global fit

Londergan & Thomas, (also B. Ma)

Search for CSV in PV DIS

Sensitivity will be further enhanced if u+d falls off more rapidly than u-d as x 1

• u-d mass difference• electromagnetic effects

•Direct observation of parton-level CSV would be very exciting!

•Important implications for high energy collider pdfs

•Could explain significant portion of the NuTeV anomaly

up (x)dn (x)?

d p (x)un (x)?

For APV in electron-2H DIS: du

du

A

A

PV

PV

28.0

u(x)up (x) dn (x)

d(x)d p (x) un (x)

Sensitivity with PVDIS

RCSV APV x APV x 0.28

u x d x u x d x

Study Higher-Twist in PVDIS

• Twist-2 (mostly) cancel in asymmetry• Twist-4 is (basically) leading twist• Clean access twist-4 effect: free from twist-2 order

dependence• Study quark-quark correlations

Coherent Program of PVDIS Study

• Measure AD in NARROW bins of x, Q2 with 0.5% precision• Cover broad Q2 range for x in [0.3,0.6] to constrain HT• Search for CSV with x dependence of AD at high x• Use x>0.4, high Q2, and to measure a combination of the Ciq’s

Strategy: requires precise kinematics and broad range

x y Q2

New Physics no yes no

CSV yes no no

Higher Twist yes no yes

2

23)1(

11 x

QxAA CSVHT

Fit data to:

C(x)=βHT/(1-x)3

PVDIS on the Proton: d/u at High x

Deuteron analysis has largenuclear corrections (Yellow)

APV for the proton has no such corrections

(complementary to BONUS)

The challenge is to get statistical and systematic errors ~ 2%

)(25.0)(

)(91.0)()(

xdxu

xdxuxaP

3-month run

Fixed Target Møller Scattering

Purely leptonic reactionWeak charge of the electron:

QWe­~­1­-­4sin2W

APV me E lab (1 4sin2 W )

(sin2 W )

sin2 W

0.05(APV )

APV

1

E lab-­Maximal at 90o in COM (E’=Elab/2)- Highest possible Elab with good P2I- Moderate Elab with LARGE P2I

Figure of Merit rises linearly with Elab

SLAC E158Jlab at 12 GeV

Unprecedented opportunity: The best precision at Q2<<MZ2 with the least theoretical

uncertainty until the advent of a linear collider or a neutrino factory

Design for 12 GeVE’: 3-6 GeV lab = 0.53o-0.92o APV = 40 ppb

Ibeam = 90 µA 150 cm LH2 target

• Beam systematics: steady progress (E158 Run III: 3 ppb)• Focus alleviates backgrounds: ep ep(), ep eX()• Radiation-hard integrating detector• Normalization requirements similar to other planned experiments• Cryogenics, density fluctuations and electronics will push the state- of-the-art

Toroidal spectrometer ring focus

4000 hours

(APV)=0.58 ppb

New Physics Reach

ee ~ 25 TeV

JLab Møller

ee­~­15­TeV

LEP200

LHC

Complementary; 1-2 TeV reach

New Contact Interactions

Does Supersymmetry (SUSY) provide a candidate for dark matter?•Lightest SUSY particle (neutralino) is stable if baryon (B) and lepton (L) numbers are conserved•However, B and L need not be conserved in SUSY, leading to neutralino decay (RPV)

Kurylov, Ramsey-Musolf, Su

95% C.L.JLab 12 GeVMøller

Two Possible Hadronization Mechanisms

RG

GY

String model

Gluonbremsstrahlungmodel